Improvement in asphalt sidewalks



UNITED vS'I'ATris vAfrmlvrfr ,Erren- SAMUEL R. SCHARF, OF WASHINGTON,DISTRICT OF COLUMBIA.

"IMPROVEMENT IN AsPHALTFslDEwALKs.

Specification forming part of Letters lfatent No. l 76,696, dated April25, 1876; application. filed March 20, 1876.

To all whom it may concern:

Be it known that l, SAMUEL It. SCHARF, of Washington, inthe county ofWashington and District oi' Columbia, have invented a new and usefulImprovement in Asphalt Sidewalk; and I do hereby declare that thefollowing is a full and 'exact description of the same, reference beinghad to the accompanying drawings, and to the letters of referencemarkedthereon. i The object of my invention is the production of asmoothand durable concrete asphalt sidewalk; and the novelty thereinconsists in the manner of making and laying the same, as more fullyhereinafter described. l In order thatV those skilled in-the art may beenabled to make my sidewalk, I proceed to describe the same, havingreference to the drawing, which represents a vertical section.

1n laying my sidewalk, the earth is excavated to a suitable depth andproperly rolled, so as to be level and smooth, all soft places being dugout and lle'd in with lhard or suitable material.

Uporni this surface thus prepared I place a base, A, constructed asfollows: Itake screened coarse gravel or broken stone, preferably thelatter, in size from one-fourth of an inch to one inch in diameter, andheat the same in any convenient way. When the same is sufciently heated`to a point about' the bbilingpoint of coal-tar, from which abou/t fourgallons of what is known as theheavy oil?" in forty gallons of coal-tarhave been distilled, I mix with such coarse gravel or stones asufficient quantity of 'such distilled coal-tar, (which has beenpreviously heated,) while the same is boiling, to thoroughly coat saidgravel orstones. y

The gravel or stone thus coated is placed hot upon the ground, preparedas described, 4to about the depth -or" one and one-half or two inches,and raked smoothly, and rolleduntil the same begins to grow stiff. A

Upon this base A, as described, I place av top course, B, prepared asfollows: I take nely-crushed stone, preferably limestone, and

pass the same through a screen hav-ing onequarter-inch meshes, and heatthe same in proper vessels. At the same time I take Trinidad or othernatural asphalt, and melt the same in a suitable vessel until it boils.I then mix with the same about one-sixth part, in bulk, of heavyparafline-oil, and stir in the same thoroughly, keeping the mixture at aboiling heat. The heated fine stone is then stirred into the mixtureabove described, the heat being maintained under the same, until thecomposition becomes of a density which will `just run and assume a levelwhen poured \upon the ground.

This composition is carried hot in suitable vessels and poured upon thebase A to the depth of from one-half inch to an inch, and leveled offand smoothed with trowels, smoothing-boards, or other proper appliances.After the same is leveled the surface is dusted With lime, or fine sand,or pulverized soap-stone,

.or other fine material of similar nature, and

smoothed off .with smoothing-boards until. it begins to set or growstiff.

` When this sidewalk is cold it is fit for use, and will be found to bevery smooth and exceedingly durable.

I am aware' that'a paving composition was patented by A. B. Vandemark in1871, wherein asphaltum and paraftine-.oil, heated together in the samevessel, have been intimately mixed with calcareous stone finely'pulverized,.and rolled smoothly and solidly,

whereby an exceedingly smooth homogeneous pavement, resembling rock, hasbeen produced.

I disclaim the invention described by said Vandemark, which differs frommine, inasmuch as he does not employ asphalt and paraffine-oil in thesame proportions, nor mix them at the. vsame temperature, that I do. Heuses line stone-dust, while I use crushed stone. He rolls vhis pavementto make it hard and smooth, while mine will not. permit rolling, andhardens by chemical action; and his pavement becomes very smooth andhomogeneous. On the contrary, mine is neither homogeneous nor smooth,and therefore less .slippery and more sufe to `travel upon in wet orfrosty weather.-

Having thus described my sidewalk, what I claim as new therein, and myin'vv'ention'7 is 1. -The sidewalk composed of the courses A and B,constructed and preparedv substantially :is described.

2. An upper course for a. sidewalk, comy posed of crushed stone,asphait, and paraffine mixed and prepared-:and laid substantially asdescribed.

This specification signed and witnessed this 18th day' of March, l187 6.

SAM UELr R. SCHARF.

Witnesses M. M. ROHRER, CHARLES THURMAN.

